The present invention relates to a timepiece including a time indicator hand which is movable between two positions to indicate two different pieces of time information.
Timepieces of this type are known in the prior art.
More specifically, EP 1 959 317 describes a timepiece which has a switch mechanism enabling the time indicator hand, for example the minute hand, to indicate two different pieces of information, such as the current time and the stop watch time, according to its movement, caused by the actuation of a push button, between a position for indicating the current time and a position indicating the stop watch time.
The switch mechanism which is described includes a transmission pinion rotated by a first moving part of the timepiece movement so as to represent a first piece of information to be displayed, and an element having a first split-second core mounted idly on the transmission pinion and rotated by the first moving part or by a second moving part of the movement so as to represent a second piece of information to be displayed.
The switch mechanism also includes a second split-second core fastened to the transmission pinion, a transmission wheel mounted idly on the transmission pinion and having a first and a second hammer biased against the first and second core respectively, a switch wheel mounted rotatably on the periphery of the transmission wheel and having a first and a second cam acting, respectively, on the first and the second hammer so as to separate, alternately, the contact between the first hammer and the first core and the contact between the second hammer and the second core respectively, in order to change the position of the transmission wheel according to the first or second piece of information to be displayed, respectively, an intermediate drive wheel being mounted idly on the transmission pinion and engaging with the switch wheel, the intermediate drive wheel being fastened to a drive wheel which can be rotated in a controlled way by means of a driving mechanism of the transmission mechanism.
The switch mechanism described in EP 1 959 317 is complex because of the use of numerous parts and their arrangement. In particular, it requires a transmission wheel with two hammers and a switch wheel with two cams.
Another switch mechanism for a timepiece enabling the minutes or the date to be indicated by the minute hand is described in CH 693 155.
This mechanism operates with a differential system and a planet gear fixed to a resetting cam, the differential system enabling an angular movement to be imparted to the minute hand to indicate a date. This mechanism is complex, and the planet carrier placed between the moving parts of the differential occupies a certain amount of vertical space.
Consequently there is a need to replace the existing switch mechanisms, and to simplify the timepiece movements, in timepieces in which a single time indicator hand can indicate two different pieces of information.